On Tue, 2013-11-19 at 16:11 +0800, Li Zhong wrote:
> I encountered following issue:
> [ 0.283035] ibmvscsi 30000015: couldn't initialize event pool
> [ 5.688822] ibmvscsi: probe of 30000015 failed with error -1
>
> which prevents the storage from being recognized, and the machine from
> booting.
>
> After some digging, it seems that it is caused by commit 4886c399da
>
> as dma_mask pointer in viodev->dev is not set, so in
> dma_set_mask_and_coherent(), dma_set_coherent_mask() is not called
> because dma_set_mask(), which is dma_set_mask_pSeriesLP() returned EIO.
> While before the commit, dma_set_coherent_mask() is always called.
>
> I tried to replace dma_set_mask_and_coherent() with
> dma_coerce_mask_and_coherent(), and the machine could boot again.
>
> But I'm not sure whether this is the correct fix...
Russell, care to chime in ? I can't make sense of the semantics...
The original commit was fairly clear:
<<
Replace the following sequence:
dma_set_mask(dev, mask);
dma_set_coherent_mask(dev, mask);
with a call to the new helper dma_set_mask_and_coherent().
>>
It all makes sense so far ... but doesn't work for some odd reason,
and the "fix" uses a function whose name doesn't make much sense to
me ... what is the difference between "setting" and "coercing"
the mask ? And why doe replacing two "set" with a "set both" doesn't
work and require a coerce ?
I'm asking because I'm worried about breakage elsewhere...
Cheers,
Ben.
> ---
> arch/powerpc/kernel/vio.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/powerpc/kernel/vio.c b/arch/powerpc/kernel/vio.c
> index e7d0c88..76a6482 100644
> --- a/arch/powerpc/kernel/vio.c
> +++ b/arch/powerpc/kernel/vio.c
> @@ -1419,7 +1419,7 @@ struct vio_dev *vio_register_device_node(struct
> device_node *of_node)
>
> /* needed to ensure proper operation of coherent allocations
> * later, in case driver doesn't set it explicitly */
> - dma_set_mask_and_coherent(&viodev->dev, DMA_BIT_MASK(64));
> + dma_coerce_mask_and_coherent(&viodev->dev, DMA_BIT_MASK(64));
> }
>
> /* register with generic device framework */
>
>
>
>
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